[web] Add cancel-loss-messaging split test (#36363)

* [web] Add cancel-loss-messaging split test

Populate the cancel confirmation step with plan-specific losses when the
cancel-loss-messaging split test is enabled: "Are you sure you want to
cancel?" heading, the subscription end date, and a card listing what the
user loses moving to the Free plan (compile timeout, AI, collaborators,
history), with the lost benefit struck through next to its Free-plan
replacement.

Shown only to non-trial Student/Standard/Pro individual subscribers with
no other retention offer (trial extension or downgrade upsell) — those
keep the existing confirmation.

Copy matches the mockups in the ticket. No new analytics events; the
existing subscription-page-cancel-button-click / subscription-cancelled
funnel is used.

Part of #35765

* [web] Consolidate ActiveSubscription stories, add cancel confirmation story

Replace the 13 fixture-per-story exports with a single Dashboard story
driven by controls (subscription fixture select, flexible licensing,
cancel-loss-messaging variant), using the CSF factories pattern. Add a
CancelConfirmation story that renders the cancel confirmation step
directly so the cancel-loss-messaging variant can be previewed without
clicking through, with a Professional fixture available to see the Pro
loss rows.

* [web] Use withSplitTests for the ActiveSubscription stories

Register cancel-loss-messaging in defaultSplitTestsArgTypes and drive the
stories' variant from the shared withSplitTests decorator (radio control,
SplitTestContext provided from args) instead of hand-rolled meta tags and
SplitTestProvider. Generalize withSplitTests' typing so it composes with
CSF factories (preview.meta) as well as legacy meta objects.

* [web] Fix Storybook indexing of the ActiveSubscription stories

Storybook's static CSF indexer requires preview.meta() to receive an
object literal, so spread withSplitTests' argTypes/decorators into the
meta literal instead of wrapping the whole config in the helper call.

* [web] Compose ActiveSubscription stories from orthogonal controls

- Wrap the stories in #subscription-dashboard-root so the dashboard's
  scoped styles (e.g. the cancel-loss strikethrough) apply in Storybook
- Replace the single fixture dropdown with independent controls (group,
  plan, period, currency, trial, status, pending plan change, add-ons,
  coupons, pending license change), building the subscription from the
  fixtures' base + patches
- Guard impossible mixes with argTypes `if` conditions: individual-only
  controls hide when group is on, and pendingLicenseChange only shows
  for groups

* [web] Add student plan to the ActiveSubscription story controls

The cancel-loss-messaging variant has student-specific rows (AI
Assistant / 10 collaborators), so the plan control needs a student
option. Groups have no student plans, so for group subscriptions the
student choice maps to the Standard group fixture.

* [web] Provide ol-plans in the ActiveSubscription stories

The cancel confirmation's downgrade branch (monthly Standard is
isEligibleForDowngradeUpsell) looks up paid-personal in ol-plans and
spins forever when the meta tag is missing. Provide ol-plans and
ol-groupPlans from the fixtures, matching the test render helper.

GitOrigin-RevId: e8491c8d39ed059e42ea3442e8d70c3ef304b009

services/web/frontend/js/features/subscription/components/dashboard/states/active/cancel-plan/cancel-subscription-loss-messaging.tsx

@@ -0,0 +1,122 @@
+import { useTranslation } from 'react-i18next'
+import { TFunction } from 'i18next'
+import MaterialIcon from '@/shared/components/material-icon'
+import OLButton from '@/shared/components/ol/ol-button'
+import { useSubscriptionDashboardContext } from '../../../../../context/subscription-dashboard-context'
+
+export type LossMessagingPlanType = 'student' | 'collaborator' | 'professional'
+
+export function getLossMessagingPlanType(
+  planCode: string
+): LossMessagingPlanType | null {
+  if (planCode.startsWith('professional')) return 'professional'
+  if (planCode.startsWith('collaborator')) return 'collaborator'
+  if (planCode.startsWith('student')) return 'student'
+  return null
+}
+
+type LossRow = { lost: string; replacement: string }
+
+function getAiLossRow(planType: LossMessagingPlanType, t: TFunction): LossRow {
+  if (planType === 'student') {
+    return { lost: t('ai_assistant'), replacement: t('no_ai_assistant') }
+  }
+  if (planType === 'collaborator') {
+    return {
+      lost: t('ai_assistant_and_higher_ai_allowance'),
+      replacement: t('small_ai_allowance_no_assistant'),
+    }
+  }
+  return {
+    lost: t('ai_assistant_and_max_ai_allowance'),
+    replacement: t('small_ai_allowance_no_assistant'),
+  }
+}
+
+function getCollaboratorsLossRow(
+  planType: LossMessagingPlanType,
+  t: TFunction
+): LossRow {
+  return {
+    lost:
+      planType === 'professional'
+        ? t('unlimited_collaborators_per_project')
+        : t('ten_collaborators_per_project'),
+    replacement: t('one_collaborator_per_project'),
+  }
+}
+
+function getLossRows(planType: LossMessagingPlanType, t: TFunction): LossRow[] {
+  return [
+    {
+      lost: t('plan_24x_longer_compile_timeout'),
+      replacement: t('basic_compile_timeout_for_small_projects'),
+    },
+    getAiLossRow(planType, t),
+    getCollaboratorsLossRow(planType, t),
+    {
+      lost: t('full_project_history'),
+      replacement: t('history_24_hours_only'),
+    },
+  ]
+}
+
+export function CancelSubscriptionLossMessaging({
+  planType,
+  terminationDate,
+  onCancelSubscription,
+  isButtonDisabled,
+  isCancelLoading,
+}: {
+  planType: LossMessagingPlanType
+  terminationDate: string
+  onCancelSubscription: () => void
+  isButtonDisabled: boolean
+  isCancelLoading: boolean
+}) {
+  const { t } = useTranslation()
+  const { setShowCancellation } = useSubscriptionDashboardContext()
+
+  return (
+    <div className="cancel-loss-messaging">
+      <h2>{t('are_you_sure_you_want_to_cancel')}</h2>
+      <p>
+        {t('cancelling_will_end_your_subscription_on', { terminationDate })}
+      </p>
+      <div className="cancel-loss-card">
+        <h3 className="cancel-loss-card-heading">
+          {t('youll_be_moved_to_the_free_plan')}
+        </h3>
+        <ul className="cancel-loss-list">
+          {getLossRows(planType, t).map(row => (
+            <li key={row.lost} className="cancel-loss-list-item">
+              <MaterialIcon type="cancel" className="cancel-loss-icon" />
+              <span>
+                <del className="cancel-loss-lost">{row.lost}</del>{' '}
+                {row.replacement}
+              </span>
+            </li>
+          ))}
+        </ul>
+      </div>
+      <div className="cancel-loss-actions">
+        <OLButton
+          variant="secondary"
+          disabled={isButtonDisabled}
+          onClick={() => setShowCancellation(false)}
+        >
+          {t('keep_subscription')}
+        </OLButton>
+        <OLButton
+          variant="danger-ghost"
+          disabled={isButtonDisabled}
+          isLoading={isCancelLoading}
+          loadingLabel={t('processing_uppercase') + '…'}
+          onClick={onCancelSubscription}
+        >
+          {t('cancel_subscription')}
+        </OLButton>
+      </div>
+    </div>
+  )
+}

services/web/frontend/js/features/subscription/components/dashboard/states/active/cancel-plan/cancel-subscription.tsx

@@ -14,6 +14,12 @@ import ExtendTrialButton from './extend-trial-button'
 import { useLocation } from '../../../../../../../shared/hooks/use-location'
 import { debugConsole } from '@/utils/debugging'
 import OLButton from '@/shared/components/ol/ol-button'
+import { useFeatureFlag } from '@/shared/context/split-test-context'
+import isInFreeTrial from '../../../../../util/is-in-free-trial'
+import {
+  CancelSubscriptionLossMessaging,
+  getLossMessagingPlanType,
+} from './cancel-subscription-loss-messaging'
 
 const planCodeToDowngradeTo = 'paid-personal'
 
@@ -136,6 +142,7 @@ export function CancelSubscription() {
   const location = useLocation()
   const { personalSubscription, plans, userCanExtendTrial } =
     useSubscriptionDashboardContext()
+  const lossMessagingEnabled = useFeatureFlag('cancel-loss-messaging')
   const {
     isLoading: isLoadingCancel,
     isError: isErrorCancel,
@@ -176,6 +183,34 @@ export function CancelSubscription() {
 
   const showExtendFreeTrial = userCanExtendTrial
 
+  // `cancel-loss-messaging` split test: show plan-specific losses instead of
+  // the bare confirmation, for non-trial individual subscribers with no other
+  // retention offer (trial extension or downgrade)
+  const lossMessagingPlanType = getLossMessagingPlanType(
+    personalSubscription.planCode
+  )
+  const showLossMessaging =
+    lossMessagingEnabled &&
+    !showExtendFreeTrial &&
+    !showDowngrade &&
+    lossMessagingPlanType !== null &&
+    !isInFreeTrial(personalSubscription.payment.trialEndsAt)
+
+  if (showLossMessaging) {
+    return (
+      <>
+        {isErrorCancel && <GenericErrorAlert />}
+        <CancelSubscriptionLossMessaging
+          planType={lossMessagingPlanType}
+          terminationDate={personalSubscription.payment.nextPaymentDueDate}
+          onCancelSubscription={handleCancelSubscription}
+          isButtonDisabled={isButtonDisabled}
+          isCancelLoading={isSuccessCancel || isLoadingCancel}
+        />
+      </>
+    )
+  }
+
   return (
     <>
       <div className="text-center">